The regions between the hydrophobic core and the polar zones of bilogical membranes (the "hydrogen belts") consist of hydrogen bond acceptors (the C=O groups of glycero- and sphingolipids) and hydrogen bond donors (the OH groups of cholesterol, sphingosine, proteins and water). We have postulated lipid-lipid and protein-lipid hydrogen bonding in these belts, and have obtained evidence indicating phospholipid cholesterol C=O...HO interaction. In further studies, we shall seek further confirmation of such hydrogen bonding, and explore the effects that changes in the composition of the hydrogen belts have on the properties and function of membranes. Model lipids are synthesized in which the groups that can partake in hydrogen bonding are abolished (e.g., O-substituted cholesterols, ether and alkyl analogs of phosphatidylcholine and lysophosphatidylcholine). Syntheses of D-isomers of choline phospholipids will be developed. The influence of these structures on membrane permeability, and its energy and entropy of activation, are determined. Monolayer experiments on the lipids, alone and in mixtures, are also performed. Lipid-transfer protein-lipid complexes are investigated in view of the possible importance of hydrogen bonding in lipid transfer. The bonding of stereoisomers of phosphatidylcholine and lysophosphatidylcholine to cholesterol will be studied by nuclear magnetic resonance and permeability experiments. The influence of lysophosphatidylcholine-OH and cholesterol-OH on vesicle-vescile fusion will be studied. Investigations will be performed on the structure and properties of cholesterol bilayers (which contain only cholesterol in their hydrophobic core) and on the properties of bilayers consisting of lysophospholipids and cholestanone.